Thirty-three Australian soldiers who were guarding the country's embassy in Iraq have been withdrawn and a Dubai-based private security firm has taken over, an embassy official said.

"We now have moved to a contractor called Unity Resources Group (URG) to provide embassy security," the official said, adding that the last soldiers left on Saturday.

The soldiers guarding the embassy were the last significant Australian troop presence in the country.

Australia once had 2,000 soldiers in Iraq, one of the larger non-US deployments.

Two Australian officers remain as advisers to the United Nations Assistance Mission for Iraq, the embassy official said.

According to its website, URG is based in Dubai and was founded by Gordon Conroy, "a former commander in the Australian SAS (Special Forces) Counter Terrorist Squadron" who is the firm's director and chief executive.

Last year, the ABC revealed URG, which handles security for the Australian embassy in Baghdad as part of a $9 million contract, is one of only two military contractors to have killed an Australian in Iraq.

The firm, with around 60 Chilean military veterans, was involved in the shooting of 72-year-old Australian Kays Juma in March 2006.

He was shot as he approached an intersection being blockaded for a convoy URG was protecting.

Professor Juma, a 25-year resident of Baghdad who drove through the city every day, allegedly sped up his vehicle as he approached the guards and did not heed warnings to stop, including hand signals, flares, warning shots into the body of his car, and floodlights.

Also in 2006, URG was involved in another shooting incident. This time two Armenian women, Genevia Antranick and Mary Awanis, were killed when their car came too close to a protected convoy.